Simplify the following expression: $x = \dfrac{y}{3} + \dfrac{y}{5}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $3$ and $5$ $\lcm(3, 5) = 15$ $ x = \dfrac{5}{5} \cdot \dfrac{y}{3} + \dfrac{3}{3} \cdot \dfrac{y}{5} $ $x = \dfrac{5y}{15} + \dfrac{3y}{15}$ $x = \dfrac{5y +3y}{15}$ $x = \dfrac{8y}{15}$